Polyphenyl ether compositions



' tions having improved oxidative stability.

3,245,907 Patented Apr. 12, 11966 3,245,907 POLYPHENYL ETHER COMPOSITIONS Louis R. Stark, East St. Louis, 111., and Roger E. Hatton, Kirkwood, Mo., assignors to Monsanto Company, a

corporation of Delaware 7 g No Drawing. Filed Aug; 28, 1961, Ser. No. 134,138

Claims; (Cl. 252-46. 4)

This invention relates to polyphenyl ether composi- More particularly, this invention relates to polyphenyl ethers stabilized against oxidative degradation by the incorporation therein of an organotin compound.

The polyphenyl ethers are compounds known to the art. It has been proposed to use the polyphenyl ethers as gas turbine (jet) engine lubricants, as hydraulic fluids, as electronic equipment coolants, as atomic reactor coolants, as diffusion pump fluids, etc., since they possess many desirable properties such as high and low temperature stability, foam resistance-and good storage stability, even I where the temperatures encountered range up to 700 F.

and higher. .-B ecause of their good balance of properties, the polyphenyl ethers have recently been receiving in creasing consideration as lubricants for jet engines. However, as the speed and altitude of operation of jet engine-- 7 containing vehicles increases, lubrication problems also increase becauseof increased operating temperatures and higher bearing pressures resulting from the increased thrust needed to obtain higher speeds and altitudes. As

. the serviceconditions encountered become increasingly shorten the useful life of a lubricant. Thus, it is a general' practice to add small amounts of other materials, or additives, to lubricants in order to affect one or more of the properties of the base lubricant. It is difficult, however, especially as operating temperatures are increased, to find additives which will still perform the function for which they are added and yet not inject other problems such as'increasing corrosion and engine deposits.

It has now been found that the-oxidative stability and thusthe useful life of thepolyphenyl ethers can be greatly extended, even under the severe conditions encountered in jet engines and other devices operating at temperatures of-the order of 600 F. and higher, by the addition to the polyphenyl ethers of an organotin compound. It is especially oteworthy that the addition of an organotin compound increases the oxidative stability of the polyphenyl others without any attendant increase in corrosion of exposed metal parts and without any appreciable increase in deposits or sludge formation. In fact, the addition of an organotin compound generally reduces the corrosivity and the amount of deposits formed when using the polyphenyl ethers alone.

It is therefore an object of this invention to provide polyphenyl ether compositions having increased resistance to oxidation. A further object is to improve the viscosity stability of polyphenyl ether compositions. A still further object is to provide polyphenyl ether compositions having increased color stability. Another object is to provide polyphenyl ether compositions which give decreased metal attack and decreased formation'of deposits and sludge.

The objects mentioned above and others, which will hereinafter be apparent, are accomplished by adding to the polyphenyl ethers an organotin compound represented dichloride, and the like.

by the structure R -Sn-X where R is an alkyl, aryl, aralkyl, arylovyaryl, biaryl, thienyl or pyridyl radical, X is a halogen or an alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl or pyridyl radical and M is a whole number from 1 to 4, and organotin compounds of the structure R SnSn-R where R is as defined above. The above structures-are used herein to include those organotin compounds where R represents one or more radicals in the same compound, for example, diphenylbenzyltin chloride.

Specific examples of organotin compounds falling within the first group of compounds defined above are tetramethyltin, tetraethyltin, trimethylethyltin, dimethyldiethyltin, diethylpropyltin chloride, dimethylethylpropyltin, triethylpropyltin, phenyltrimethyltin, diphenyldimethyltin, phenyltriethyltin, diphenyldipropyltin, 'dibutyldiphenyltin, tetrabutyltin, tetrahexyltin, tetraoctyltin, phenyltrioctyltin, tetradecyltin, tetralauryltin, tetrapentadecyltin, tetraoctadecyltin, dibutyldiphenyltin, butyldiphenyltin chloride, dioctyldiphenyltin, triphenyltin chloride, triphenyltin bromide, triphenyltin fluoride, triphenyltin iodide, diphenyltin dichloride, diphenyltin dibromide, benzyldiphenyltin chloride, tetraphenyltin, tetrabenzyltin, dibenzyltin dichloride, benzyltriphenyltin, diben zyldiphenyltin, dibenzyldidecyltin, diphenyldinaphthyltin, tetranaphthyltin, bis(p-phenoxyphenyl)diphenyltin, tetrakis phenoxyphenyltin, tetrathienyltin, diphenyldithienyltin, triphenylthienyltin, dibenzyldithienyltin, tetrapy'ridyltin, diphenyldipyridyltin, dibenzyldipyridyltin, dibenzyldithienyltin, diethyltin dichloride, dipyridyltin dichloride, diphenyldibiphenyltin, tetrabiphenyltin, dibiphenyldiphenox'yphem yltin, diphenoxyphenyltin dibromide, diphenoxyphenyltin Examples ofcompounds falling within the second group defined above are hexaphenylditin, hexabutylditin, hexabenzylditin and the like. The additive chosen should, of course, not be volatile at the temperatures to be encountered in a particular application.

Generally the organotin compounds of the structure R -Sn-X can be prepared by the action of a Gignard reagent or an organolithium compound on stannic chloride. Also, tetraalkyltin compounds can be prepared by the action of a dialkylzinc on stannic or stannous chloride. Other methods include treating partially alkylated or partially arylated tin halides with a Grigriard reagent or an organolithium reagent. The ditins can be prepared by the action of a Grignard reagent onstannous chloride.

The polyphenyl ethers to which this invention pertains can be represented by the structure where n is a whole number from 2 to 5. The preferred polyphenyl ethers are those having all their ether link-- ages in the meta position since the all-meta linked ethers are the best suited for many applications because of their wide liquid range and high degree of thermal stability. However, mixtures of the polyphenyl ethers, i.'e. either isomeric mixtures or mixtures of homologous ethers, can also be used to obtain certain properties, 'e.-g. lower solidification points. Examples of the polyphenyl ethers contemplated are the bis(phenoxyphenyl)ethers, e.g. bis(m-phenoxyphenyl)ether, the bis(phenoxyphenoxy)- benzenes, e.g. m bis(m phenoxyphenoxfibenz'ene, m bis( p phenoxyphenoxy)benzene, o bis(o phenoxyphenoxy)benzene, the bis(phenoxyphenoxyphenyl)- ethers, e.g. bis[m (m phenoxyphen-oxy')phenyl]- ether, bis[p-(p-phenoxyphenoxy)phenyl]ether,- m-[(mphenoxyphenoxy) (o-phenoxyphenoxy)]ether and the bis- (phenoxypheno'xyphenoxy)benzenes, e.g. m-bis[m-(mphenoxyphenoxy phenoxy] benzene, p-bis p- (m-phenoxyphenoxy)phenoxy]benzene, m bis[m-(p-phenoxyphen oxy)phenoxy] benzene. It is also contemplated that mixtures of the polyphenyl ethers can be used. For example, mixtures of polyphenyl ethers in which the non-terminal phenylene rings (i.e. those rings enclosed in the brackets in the above structural representaton of the polyphenyl ethers contemplated) are linked through oxygen atoms in the meta and para positions, have been found to be particularly siutable as lubricants because such mixtures possess lower solidification points and thus provide compositions having wider liquid ranges. Of the mixtures having only meta and para linkages, a preferred polyphenyl ether mixture of this invention is the mixture of S-ring polyphenyl ethers where the non-terminal phenylene rings are linked through oxygen atoms in the meta and procedure, steel, copper, silver, titanium, magnesium alloy and aluminum alloy. However, only the results upon magnesium alloy, copper and silver are reported since the compositions tested had essentially no effect on steel, titanium and aluminum alloy. In some tests no metal specimens were included and only the viscosity increase was measured. The results observed using the above-described procedure are recorded in the table below. Viscosity measurements were made according to ASTM Method D-445-53T using a Cannon-Fenske modified Ostwald viscosimeter. The percentage of viscosity increase was determined by taking the difference in viscosity of a composition before and after it was heated, dividing that difference by the original viscosity and multiplying the quotient 'by 100. The corrosivity to metals was determined by weighing the metal specimens before and after the test.

Organotin Additive Viscosity Increase, Weight Change, mg.

Percent per sq. cm. Composi- Polyphenyl Ether tion N 0.

Description Patient 100 F. 210 F. Mg Cu Ag 1 A mixture of m-bls(m-phenoxyphenoxy)ben- N one-control 103 37 +0. 22 3. 60 +2. 88

zene 65% by wt.; m-[(m-phenoxy henoxy) I (p-ghenoxyphenoxyflbenzene, b Wt.; 111- is(ophenoxyphenoxy)benzene, 5%, by wt.

do Tetraphenyltin 0. 1 24 11 +0. 30 0. 22 0. 02 do". do 0. 2 23 1 +0. 01 0. 08 +0. 04 do 1. 0 27 15 +0. 03 0. 05 0. 02 Triphenyltin chloride. 0. 5 62 27 --0. 30 1. 90 0. 38 Diphenyltin dichloride 0.5 90 34 0. 38 2. 96 0. 87 Dibenzyltin dlchlorid 0. 5 45 18 +0. 44 l. 7 --0. 20 Tetrnbutyltin 0. 5 62 27 +0. 03 0. 65 -0. 19 Dibutyldiphenyltirn- 0. 5 60 27 +0, 01 0. 17 0. 18 Hexaphenylditin 0. 5 22 Tetraphenyltin. 0. 2 l9 5 N one-eontrol Tetraphenyltin 14 do o 15 A mixture of bis(m-phenoxyphenoxy)ether, None-e0ntr0l...,

about 37% by weight; [(m-phenoxyphenoxy) (p-phenoxyphenoxy)lether, about 38% by weight; o-phenoxyphenoxy) (m-phenoxyphenoxy) ether, about by weight; [(0- phenoxyphenoxy) (p-phenoxyphenoxyhether, about 5% by weight. 16 do Tetraphenyltin 0. 2 5 5 +0. 04 0. 16 +0. 01 17 A mixture of rn-bis(m-phenoxyphenoxy)ben Tetra-p-phenoxyphenyltin.- 0. 1 10 +0. 01 +0. 22 0. 01

zene, 65% by weight; m-[(m- )henoxyphenoxy) (pphenoxyphen0xy)]benzens, by weight; m-bis(p-phenoxyphenoxy) benzene, 5% by weight. 18. do Tetra-p-phenoxyphenyltin- 0. 5 14 7 do 1. 0 17 10 +0. 01 0. 03 0. 07 Bis(phenoxyphenyl)di- 0. 6 12 8 0 0. 27 0. 06

phenyltin. do 0. 5 17 8 No metals present.

para position and composed, by weight, of about 65% m-bis(m-phenoxyphenoxy)benzene, 30% m-[(m-phenoxyphenoxy)(p-phenoxyphen Xy)] enzene and 5% mbis(p-phenoxyphenoxy)benzene. Such a. mixture solidifies at about -10 F. whereas the three components solid- .ify individually at temperatures above normal room temperatures.

The aforesaid polyphenyl ethers can be obtained by the Ullmann ether synthesis which broadly relates to ether-forming reactions of e.g., alkali metal phenoxides such as sodium and potassium phenoxides with aromatic halides such as bromobenzene in the presence of a copper catalyst such as metallic copper, copper hydroxides, or copper salts.

The major bench scale method used for evaluating the oxidative stability of a lubricant is the procedure given in MIL-L-9236A according to which the lubricant to be tested is heated at a specified temperature in the presence of certain metals and oxygen and the viscosity increase of the lubricant is determined. Additionally, information as to the corrosivity of a lubricant to metals can also be obtained.

Various polyphenyl ether compositions were tested according to the procedure of MIL- L-9236A except that the temperature was held at 600 F. instead of 500 F. and the metal specimens used were, as specified in said From the above it is clearly evident that the addition of an organotin compound to the polyphenyl ethers provides polyphenyl ether compositions having a greatly increased oxidative stability and therefore a greatly extended useful life. In regard to the extension of useful life, it has been found that the test procedure described above correlates quite well with the results obtained under full scale aircraft gas turbine bearing tests and under conditions of actual use. It has been found that the magnitude of change in the viscosity at F. as measured by the test procedure is representative of the extent of increased service life obtainable under actual conditions. Thus, for example, the decrease in viscosity increase at 100 F. otbained by the use of tetraphenyltin in a mixture of S-ring polyphenyl ethers was on the order of about 4 times (ie the viscosity increase at 100 F; for composition No. 1 as compared to the viscosity increase for com positions Nos. 24 was about 4 times as great). Based on these results in the bench test it would be expected that a service life increase of about 4 times that obtained from the mixture of S-ring polyphenyl ethers used can be obtained by the addition to said mixture of tetraphenyltin. Similar correlations are obtained with the other organotin compounds contemplated.

It is also evident from the data presented above that the addition of an organotin compound to the polyphenyl and increased sludge formation.

ethers provides polyphenyl ether compositions having significantly reduced rates of corrosion to metals (weight loss) and reduced varnishing. It was also noted, by visual inspection, that the organotin stabilized polyphenyl ethers had significantly less sludge than did the unstabil- :ized polyphenyl ethers. The decreased metal attack experienced by the addition of an organotin compound to the polyphenyl ethers is in .and of itself a significant aspect of the'invention since normally the best that is hoped for or expected is that an additive added for a particular purpose, such as to prevent oxidation, does not also cause other problems such as increased corrosion Thus, with respect to this invention, it is unexpected that the addition of an organotin compound to the polyphenyl ethers not only gives protection for the purpose for which it was added, namely, increased oxidative stability, but also that the same additives result in decreased corrosion and sludge formation.

The improved polyphenyl ether compositions of this invention can be obtained by the addition to the polyphenyl ethers of at least about 0.01% by weight of an organotin compound as described above. Since the amount of organotin compound added above the minimum amount mentioned has little or no elfect on the degree of stabilization obtained, considerations other than stabilization have to be taken into account in selecting the quantity of organotin compound to be added to a particular polyphenyl ether. As a practical matter, about by weight of an organotin compound is the maximum amount to be used although it is preferred to use from about 0.05% to about 1% by weight, since within that range of concentrations the amount of additive used is low enough so that solubility considerations are not limiting yet there is no significant difference in the degree of stabilization obtained. Because of the various considerations which go into the choice of the amount of organotin compound used and also because of the slight differences existing between various polyphenyl ethers and mixtures thereof, the amount of organotin compounds used can be expressed as a stabilizing amount," i.e. an amount which is effective to provide an increase in the oxidative stability of the polyphenyl ether compositions contemplated.

It is also contemplated that other additives such as pour point depressants, crystallization suppressants, viscosity index improvers, dyes, rust inhibitors and materials to improve extreme pressure properties can be added to the compositions of this invention.

Other modes of applying the principles of this invention will be apparent to those skilled in the art. Accordingly, while this invention has been described with reference to various specific examples and embodiments, it is understood that the invention is not limited to such examples and that it may be variously practiced within the scope of the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

. 1. A composition comprising a major proportion of a polyphenyl ether represented by the structure .j ol L J.

where n is an integer from 2 to 5, and a stabilizing amount of an organotin compound selected from organotin compounds represented by the structure R -Sn-X and R;,Sn4n-R where R is selected from the group consisting of alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals, M is a whole number from lto 4 and X is selected from the group consisting of halogen and alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals.

6 2. A composition of claim 1 where R is 'analkyl radical.

3. A composition of claim 1 where R is phenyl. 4. A composition of claim 1 where R is benzyl. 5. A composition comprising a major proportion of a polyphenyl ether represented by the structure where n is an integer from 2 to 5 and a stabilizing amount of tetraphenyltin.

6. A composition comprising a major proportion of m-bis-m-phenoxyphenoxy)benzene and a stabilizing amount of an organotin compound selected from organotin compounds represented by the structure and R -SnSn-R where R is selected from the group consisting of alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals, M is a whole number from 1 to 4 and X is selected from the group consisting of halogen and alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals.

7. A composition of claim 6 where the organotin compound is tetraphenyltin.

8. A composition of claim 6 where R is phenyl.

9. A composition comprising a major proportion of a mixture of 5-ring polyphenyl ethers wherein the nonterminal phenylene radicals are linked through oxygen in the meta and para positions and a stabilizing amount of tetraphenyltin.

10. A composition comprising a major proportion of a mixture of S-ring polyphenyl ethers having by weight about m-bis(m-phenoxyphenoxy)benzene, 30% m-[ (m-phenoxyphenoxy) (p phenoxyphenoxy) benzene and 5% m-bis(p-phenoxyphenoxy)benzene and a stabilizing amount of an organotin compound selected from organotin compounds represented by the structure R -SnX and R -Sn-Sn--R where R is selected from the group consisting of alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals, M is a whole number from 1 to 4 and X is selected from the group consisting of halogen and alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals.

11. A composition of claim 10 where R is phenyl.

12. A composition comprising a major proportion of a mixture of S-ring polyphenyl ethers having by weight about 65% m-bis(m-phenoxyphenoxy)benzene, 30% rn-[ (m-phenoxyphenoxy) (p phenoxyphenoxy) benzene and 5% m-bis(p-phenoxyphenoxy)benzene and from about 0.05% to about 1% by weight of tetraphenyltin.

13. A composition of claim 6 where R is benzyl.

14. A composition comprising a major proportion of bis[(m-phenoxyphenoxy)phenyl]ether and a stabilizing amount of an organotin compound selected from organotin compounds represented by the structure and R Sn-Sn--R where R is selected from the group consisting of alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals, M is a whole number from 1 to 4 and X is selected from the group consisting of halogen and alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals.

15. A composition comprising a major proportion of bis[(m-phenoxyphenoxy)phenylJether and from about 0.05% to about 1% by weight of tetraphenyltin.

16. A composition comprising a major proportion of 4-ring polyphenyl ether and a stabilizing amount of an organotin compound selected from organotin compounds represented by the structure RHn-X and R -SnSnR where R is selected from the group consisting of alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals, M is a whole number from 1 to 4 and X is selected from the group consisting of halogen and alkyl, aryl, aralkyl, aryloxyaryl, biaryl, thienyl and pyridyl radicals.

17. A composition comprising a major proportion of a mixtureof 4-ring polyphenyl ethers and from about 0.05% to about 1% by weight of tetraphenyltin.

18. A composition comprising a major proportion of a 7-ring polyphenyl ether and from about 0.05% to about 1% by weight of tetraphenyltin.

19. A composition comprising a major proportion of a mixture of S-ring polyphenyl ethers wherein the nonterminal phenylene radicals are linked through oxygen in the meta and para positions and from about 0.05% to about 1% by weight of hexaphenylditin.

20. A composition comprising a major proportion of a mixture of S-ring polyphenyl ethers wherein the nonterminal phenylene radicals are linked through oxygen in the meta and para positions and from about 0.05% to about 1% by weight of tetrabutyltin.

References Cited by the Examiner UNITED STATES PATENTS 2,112,305 3/ 1938 Rosen 252-400 2,181,914 12/1939 Rosen 252-400 2,219,463 10/1940 Yngve 260429.7 2,236,910 4/1941 Lincoln et a] 260429.7 2,267,779 12/1941 Yngve 260429.7 2,940,929 6/ 1960 Diamond 25233.6

OTHER REFERENCES Aftergut et al.: Amorphous Aromatic Compounds: The Phenoxypoly (m-Phenoxylene) Benzenes, Chemistry and Industry, August 29, 1959, pages 1090-91.

Chopey: Bis (m-Phenoxyphenyl) Ether," Chemical Engineering, vol. 67, No. 9, May 1960, pages 77-78.

DANIEL E. WYMAN, Primary Examiner.

JOSEPH R. LIBERMAN, Examiner. 

1. A COMPOSITION COMPRISING A MAJOR PROPORTION OF A POLYPHENYL ETHER REPRESENTED BY THE STRUCTURE 